Prosthodontic restorative systems and techniques are well-known in the prior art. For partially or fully edentulous patients, a dental implant fixture is implanted in a cylindrical bore made in the alveolar ridge crest of a patient's jawbone after the gum tissue has been displaced. The fixture typically includes an internally-threaded cylindrical socket which receives one or more components used for attaching a permanent dental restoration to the fixture. The components typically include an abutment base in the form of a short tubular body having a transverse wall at a first end thereof shaped to mate with the gingival aspect of a transverse surface of the implant fixture. The abutment base has a bore therethrough for receiving an abutment screw used to retain the abutment base to the fixture. A coping is retained in the abutment screw using a coping screw. A dental restoration, in the form of an anatomical overlay, is adapted to be fabricated to the coping. Such systems are shown in U.S. Pat. Nos. 4,645,453 and 5,078,607 to Niznick.
The various components of the dental prosthodontic restoration are typically driven and tightened with respect to the implant mixture or each other using a plurality of different drivers, one for each type of component. The prosthodontist manipulates the drivers manually or through the use of an automatic device.
Precise and complete tightening of the components in a restoration is often difficult to achieve manually. Thus, the components often loosen and back-out of their fittings, requiring repeated office visits for the retightening. To combat the loosening or unscrewing of the implant/prosthetic system a pre-determined pre-load needs to be applied to the engaged threads. To accomplish this process several torsional ratchet tools have been designed. Of these tools, a few incorporate a breakaway feature to generate the desired torque and prevent the seating tool or screw from stripping. Although these breakaway ratchets meet the desired functional requirements, due to wear they do not maintain their calibration after continuous use. Furthermore, incorporating this breakaway feature into the available ratchets has made the final tool's cost, size, sterility and ease of use prohibitive as the systems contain many intricate moving components. An attempt to overcome many of the shortcomings of the prior art is shown in U.S. Pat. No. 5,158,458 which employs a torque element having a plurality of spokes, all of which break to provide the torque limit.
There is therefore a need to provide a new system for driving components used in a dental prosthodontic restoration that overcomes these and other problems of the prior art.